Hyperpigmentation of skin may lead to darkened areas such as freckles, age spots, ‘café au lait’ spots, or ‘bags’ under the eyes. Hyperpigmentation can result from a variety of factors such as UV exposure, aging, stress, etc. These factors can lead to an excess production of melanin, or melanogenesis, in the skin by melanocytes, which can lead to formation of hyperpigmented areas.
There may be a demand for cosmetic products that can lighten the appearance of skin, either for overall lightening of the complexion or for lightening particular hyperpigmented regions thereof such as large freckles, ‘café au lait’ spots, or ‘bags’ under the eyes that may result from excessive local amounts of pigment in the skin. Many topical formulations are being marketed that claim to lighten age spots and reduce the effects of hyperpigmentation. However, these cosmetic formulations may have questionable effectiveness.
Hypopigmentation of skin tissue has been observed in response to temporary cooling or freezing of the tissue, such as may occur during cryosurgery procedures. Such hypopigmentation effects that can be generated by contact cooling are described, e.g., in Y. Har-Shai et al., “Effect of Skin Temperature on Skin Pigmentation During Contact and Intralesional Cryosurgery of Keloids,” JEADV 2007, 21, 191-198 (2006). Loss of pigmentation following skin cooling or freezing may result from decreased melanosomes production, destruction of melanocytes, or inhibited transfer of melanosome into the keratinocytes in the lower region of the epidermal layer. The resultant hypopigmentation may be long-lasting or permanent.
Accordingly, there may be a need for methods and apparatus that can provide controlled and/or gradual lightening of skin tissue that can address and/or overcome at least some of the deficiencies or issues described herein above.